Construction and mining equipment and machinery often operates in terrain that can vary in pitch and work surface grades. In such terrain, it is often desirable to level a machine with respect to a reference plane, such as the horizon or an angled plane. Traditionally, leveling of machines, for example, mining equipment such as rotary drills, is accomplished using four leveling jacks connected to the main frame near the frame's corners. An operator will often achieve side-to-side leveling using, e.g., only the left and right rear jacks, and then use the left and right front leveling jacks to complete front-to-back leveling. During some leveling adjustments, however, the frame and other machine components can be exposed to unwanted stress and fatigue due to frame torsion and other forces. For example, if the rear leveling jacks are used to achieve side-to-side leveling, as discussed above, damaging frame twisting can occur and, in extreme cases, one or more of the leveling jacks can be lifted off the work surface.
Some previous attempts to address this problem use three leveling jacks instead of four, so that the frame is free to pivot about the single front leveling jack when side-to-side leveling is conducted by the rear leveling jacks. Such systems, however, may provide decreased stability as opposed to systems having a frame with four leveling jacks.